Ophiolites, fragments of oceanic lithosphere exposed on land, are typically found as isolated klippen in intensely deformed fold-thrust belts spanning hundreds to thousands of kilometers along-strike. Ophiolites whose geochemistry indicates that they formed above subduction zones, may have been relics of larger, once-coherent, oceanic lithosphere tracts that formed the leading edge of an upper plate below which subduction occurred; such tracts were subsequently dismembered by deformation and erosion during orogenesis and uplift. However, to what extent the first-order original coherence is maintained between ophiolitic klippen is difficult to assess. Here, we aim to evaluate whether the Jurassic forearc ophiolites overlying subduction complex rocks in California, now scattered over 1000 km and dismembered by the wider San Andreas Fault Zone, still maintain their original lithospheric coherence. To this end we (i) compile available crustal ages from all ophiolite klippen exposed in the Jurassic ophiolite belt of the western United States; (ii) review and kinematically reconstruct post-middle Jurassic deformation that occurred between the modern western coast and the stable North American craton to restore the original positions of the ophiolite fragments relative to each other and to North America, and (iii) perform a paleomagnetic analysis of a sheeted dyke sections of the Mt. Diablo and Josephine ophiolites to estimate the orientation of the spreading axis at which the Jurassic Californian forearc ophiolites formed. The latter analysis reveals that the original ridge orientation likely trended ∼080–260°, near-perpendicular to the orientation of the trench along the western margin of the ophiolite belt. We show that with these constraints, a straightforward ridge-transform system can explain the age distributions of the ophiolites with spreading rates of 6–7 cm/a. Our analysis shows that the Jurassic ophiolites of California may be considered klippen of a single sheet of oceanic lithosphere that accreted at a supra-subduction zone spreading ridge. In addition, we show that kinematic and paleomagnetic analysis of ophiolite belts may provide novel constraints on the kinematic evolution of accretionary orogens and the plates now lost to subduction.

蛇绿岩是暴露在陆地上的海洋岩石圈碎片，通常在沿走向跨越数百至数千公里的强烈变形的褶皱逆冲带中以孤立的飞跃岩形式被发现。地球化学表明它们形成于俯冲带之上的蛇绿岩可能是更大的、曾经连贯的海洋岩石圈带的遗迹，这些岩石圈带形成了上板块的前缘，俯冲低于该板块；这些区域随后在造山运动和隆升过程中因变形和侵蚀而被肢解。然而，蛇绿岩飞跃之间的一级原始相干性在多大程度上难以评估。在这里，我们的目的是评估侏罗纪前弧绿岩是否覆盖在加利福尼亚的俯冲复杂岩石上，现在分散在 1000 多公里处并被更广泛的圣安德烈亚斯断层带肢解，仍然保持着它们原有的岩石圈相干性。为此，我们（i）从美国西部侏罗纪蛇绿岩带中暴露的所有蛇绿岩飞跃岩中收集可用的地壳年龄；(ii) 审查和运动学重建现代西海岸和稳定的北美克拉通之间发生的后中侏罗世变形，以恢复蛇绿岩碎片相对于彼此和北美的原始位置，以及 (iii) 执行古地磁分析了 Mt. Diablo 和 Josephine 蛇绿岩的片状堤坝部分，以估计侏罗纪加利福尼亚弧前蛇绿岩形成的扩展轴的方向。后一种分析表明，最初的脊线方向可能趋向于 ∼080–260°，几乎垂直于沿蛇绿岩带西缘的海沟方向。我们表明，在这些约束条件下，一个简单的山脊变换系统可以解释扩展率为 6-7 cm/a 的蛇绿岩的年龄分布。我们的分析表明，加利福尼亚的侏罗纪蛇绿岩可能被认为是单片大洋岩石圈的飞跃，它在上俯冲带扩张脊处增生。此外，我们表明，对蛇绿岩带的运动学和古地磁学分析可能会为增生造山带的运动学演化提供新的约束，并且板块现在因俯冲而消失。我们的分析表明，加利福尼亚的侏罗纪蛇绿岩可能被认为是单片大洋岩石圈的飞跃，它在上俯冲带扩张脊处增生。此外，我们表明，对蛇绿岩带的运动学和古地磁学分析可能会为增生造山带的运动学演化提供新的约束，并且板块现在因俯冲而消失。我们的分析表明，加利福尼亚的侏罗纪蛇绿岩可能被认为是单片大洋岩石圈的飞跃，它在上俯冲带扩张脊处增生。此外，我们表明，对蛇绿岩带的运动学和古地磁学分析可能会为增生造山带的运动学演化提供新的约束，并且板块现在因俯冲而消失。